1. Technical Field
Embodiments described herein relate generally to a sanitary washing device, and more particularly to a sanitary washing device for washing with water the “bottom” and other parts of a user seated on a sit-down toilet.
2. Background Art
When a washing nozzle for private parts washing squirts wash water at the private parts, at least part of the washing nozzle is exposed (advanced) outside from a casing installed with prescribed functional components including the washing nozzle and a hot water tank. Hence, dirt and dirty water may be attached to the washing nozzle. In this context, there is a sanitary washing device which cleans away dirt and dirty water attached to the washing nozzle before and/or after private parts washing. Thereby, the washing nozzle is kept clean.
However, in a humid environment such as a toilet room, even after dirt and dirty water attached to the washing nozzle are cleaned away, bacteria may grow on the washing nozzle over time. More specifically, bacteria such as methylobacteria, called pink slime, and black mold grow on the bowl surface of the toilet stool. Such bacteria may be attached to the washing nozzle, and multiply thereon. Multiplication of bacteria results in an aggregation of bacteria and their secretion (slime, black stain), called biofilm. The biofilm is difficult to remove by the normal nozzle cleaning as mentioned above.
In this context, Japanese Patent No. 3487447 proposes a sanitary washing device. In this sanitary washing device, an electrolytic cell is connected to a flow channel for supplying wash water. The electrolytic cell produces water containing hypochlorous acid. This water is regularly supplied to sterilize the washing nozzle so as to avoid biofilm formation. Here, hypochlorous acid is produced by electrolysis of chlorine ions in tap water. However, the concentration of chlorine ions in tap water varies with geographical area. Hence, there is demand for ensuring the concentration of hypochlorous acid required to sterilize the washing nozzle even for a lower concentration of chlorine ions in tap water.
In this context, International Publication Pamphlet WO 95/32922 proposes an electrolyzing device and electrolyzing method for producing water containing hypochlorous acid. This document describes the relationship between current density and chlorine generation efficiency. According to this document, higher current density results in higher chlorine generation efficiency, and the chlorine generation efficiency is maximized at current densities within a certain range. However, if the current is increased to increase the chlorine generation efficiency to ensure the concentration of hypochlorous acid, the load on the electrodes of the electrolytic cell increases. In this respect, there is room for improvement. Furthermore, in view of the electrode lifetime, increased load on the electrodes is not very desirable for a sanitary washing device having electrodes with a relatively small area.
On the other hand, JP-A 9-144103 (Kokai) discloses a toilet unit with a sterilizing water supply function. In this toilet stool, sterilizing water is produced by a continuous electrolytic cell. At appropriate timing, a sterilizing water control circuit supplies the sterilizing water to a toilet bowl through a sterilizing water piping to sterilize bacteria in the toilet bowl. According to this document, the free chlorine concentration in the sterilizing water can be controlled by adjusting the flow rate of water flowing in the interelectrode path of the continuous electrolytic cell. Thus, for example, even for a lower concentration of chlorine ions in tap water, the concentration of hypochlorous acid required to sterilize the washing nozzle can be ensured by reducing the flow rate of supplied water. On the other hand, even for a higher concentration of chlorine ions in tap water, demand for sterilizing water with higher concentration is met by reducing the flow rate of supplied water.
However, if the flow rate of supplied water is reduced, the flow rate of water for cleaning the washing nozzle is also reduced. The washing nozzle is typically provided with a plurality of water discharge ports, and flow channels respectively corresponding to the plurality of water discharge ports. If the sterilizing water is produced with lower flow rate of supplied water and passed through all the flow channels, then the concentration of sterilizing water can indeed be increased. However, the force of cleaning away dirt and dirty water attached to the washing nozzle, i.e., the force of removing dirt and dirty water from the washing nozzle, may be insufficient.